GSC 0396 1222 is a probable Algol - resend

[jg <jg@jgws.freeisp.co.uk>]

The following didn't make it first send attempt for some reason, didn't
bounce either (maybe due to being my first email of that day???), so I'm
resubmitting it without the email attachment.  You'll just have to
imagine the graph I'm afraid ;')

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NOTE: someone, somewhere on one of the lists I check out from time to
time but do not subscribe to, asked if there was anything for visual
variable star observers that could come out of the current TASS data.
If anybody remembers who this is could they forward this mail to them,
as I don't think they're on TASS list.  Thanks.
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Data is from Tom's "July" GPLesque-open-source data release.


GSC 0396 1222 has observations for 4 nights (plus a very small number
for a fifth night that don't effect the overall point but will be
ignored here).

On one of these nights there is a roughly 1.1 magnitude dip in V, and
around +0.4 reddening in V-I.

Unfortunately this latter is only from 11 observations spanning around
54 minutes and insufficient to give much indication of lightcurve
behaviour, so other independent effects on that night that did not occur
on the other nights could be responsible.

Therefore GSC 0396 0166 lying at around 7 arcmins, which has a similar
number of observations covering the same 4 nights, is used as a check
star.  Any anomalous weather or other behaviour on the night in question
would be expected to affect both stars, not just one of them.

The situation is easiest depicted by the attached graph (small gif)
where x axis is JD, y axis V mag, dots are GSC 0396 1222, the suspected
Algol (ie type EA), and + symbols the "check star" GSC 0396 0166.

This object is not in any variability catalogues that I can see.  I band
data suggests that the eclipse may have been near minimum, but V band
data is a bit too scattered to comment (Tom did say limiting magnitude
was not as deep in Summer).  To have caught it exactly at minimum is a
bit coincidental though.

This would be an excellent candidate for visual observers to follow up.
There is no indication whatsoever with one minimum as to when any next
eclipse would occur.  If this star was included as part of a visual
programme any future eclipse seen would be a _confirmation_ observation,
as it is as yet not even certain that the detection is valid (though
looking fairly likely).  The observing regimes visual observers follow
are the ones most likely to come across such an occurrence, and the
amplitude of variation sufficient for any detected eclipse to be evident
enough.  A handful of eclipses are needed to be able to guesstimate a
preliminary period.

Cheers

John

John Greaves

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